A technique of using multiple receiving apparatuses and multiple wireless terminals to determine the position of a wireless terminal is known (for example, refer to Japanese Laid-Open Patent Publication No. 2007-221541). Further, a radio frequency identification (RFID) system that uses multiple monitoring apparatuses and multiple nodes (wireless sensor, etc.) is known (for example, refer to Japanese Laid-Open Patent Publication No. 2010-213278).
According to another known technique, in an ad hoc network, the distances between a mobile terminal apparatus and multiple base stations are estimated based on the hop counts from the mobile terminal apparatus to the base stations, and based on a result of the estimation, the position of mobile terminal apparatus is estimated (for example, refer to Japanese Laid-Open Patent Publication No. 2006-229845). Further, a known sensor network (wireless sensor network) is a wireless network in which multiple wireless terminals equipped with sensors are scattered and the wireless terminals cooperate to obtain an environment or a physical state.